Electron discharge device



15, 1935- B. SALZBERG I ELECTRON DISCHARGE DEVICE Filed March 6, 1935INVENTOR BERNARD SALZBERG Patented Oct. 15, 1935 UNITED STATES- PATENTOFFICE 2,011,549 atroraon mscmmor nnvrcn Bernard Salzberg, East Orange,

by memo assignments, to Radio America, New York, N.

Delaware Application March 6, 1935,

4 Claims.

tional tube will operate is limited principally by a ing electrodessmall,

interelectrode and interlead capacity and by the inductance of the leadsto the electrodes because the inductance and capacity of the electrodesand leads form an electric system which determines the upper limit offrequency at which the tube will operate. While the interelectrodecapacity may be decreased and the upper frequency limit at which a tubewill operate increased by makmaking them short and bringing out theleads at different points of the bulb, such a tube is make because ofspecial constructions and methods required for assembling such tubes.Where the electron discharge device is of the multi-grid type, itbecomes diilicult to provide proper shielding between the variouselements in the tube, particularly between the control grid lead and theanode. Shielding becomes important at the very high frequencies at whichthe tubes are intended to operate.

An object of my invention is to provide an electron discharge devicewhich may be made commercially even in very small sizes and in which theinterlead capacity and the inductance of the leads are considerably lessthan in the conventional type. Another object of my invention is toprovide an electron discharge device of the type described in which theoverall dimensions and interelectrode spacing is much less than isfeasible with tubes constructed in the usual way. A still further objectof my invention is to provide an electron discharge device of the typedescribed in which the various elements and leads are properly shieldedfrom one another.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims, but theinvention itself will best be understood by reference to the following.description taken in connection with the accompanying drawing in whichFigure 1 is a perspective view with parts broken away of the electrodemountassembly of an electron discharge device embodying my invention;Figure 2 is a vertical section of the electrode mount assembly shown inFigure 1; Figure 3 is a bottom plan view of the electrode mount assemblyshown in Figure 2; and Figure 4 shows an electron discharge device madein accordance with my invention and mounted in a shielded type ofsocket.

The envelope ill of the tube shown in Figure 4 encloses and supports aunitary electrode mount assembly shown in detail in Figures 1 to 3inclusive and comprising an indirectly heated cathode ll,'a control gridl2, a screen grid l3, suppressor grid 14 and an anode it, which maydiflicult and expensive to N. 1., assignor, Corporation of 2., acorporation of Serial No. 9,543

' be a box-like structure made from sheet metal. The anode I5 isprovided with a pair of flat side rods it which could be made integralwith the plate and which have shoulders ii for supporting electrodespacers i8 and IQ of insulation such as mica and preferably in the formof plates or discs transverse to the longitudinal axis of the electrodemount. The shoulders I! are bent over onthe outside of and against themica plate members and may lie in slots in the edges of the 10 platemembers as shown to rigidly secure the spacers to the anode so as toprovide a rigid and unitary electrode assembly.

In accordance with my invention described and claimed in my copendingapplication Serial No. 732,028 filed June 23, 1934 and assigned to theRadio Corporation of America, radially positioned stifi conductors 20.which serve as lead-ins and mount support wires, extend thru an annularpress 2! in the wall of the envelope "I as shown in Figure 4 and havesecured to their inner ends, preferably by welding, U-shaped conductors22 having one end threaded thru apertures 23 in the insulating disc orplate It to secure the conductors 2|! to the plate member as best shownin Figure 1, one end 24 of conductor 22 being formed to engage thebottom of the insulating plate l9 and the other end 25 beingelectrically connected to one of the electrodes mounted between theplates l8 and 19. The outer ends of the conductors 20 serve as tubecontacts, as best shown in Figure 4, to be' received in a properlydesigned socket. This construction eliminates the need of the usualreentrant stem press and materially reduces the overall dimensions ofthe tube. It will be observed that the control grid lead 26, and theanode lead 21, are positioned to extend from opposite ends of theenvelope to reduce interlead capacity and inductance and to separate theinput and output leads as much as possible. The getter tab 28 ispreferably secured to the upper end of the mount. It is formed to directthe getter against the side wall of the envelope.

In accordance with my invention shielding is provided to shield theanode and its lead from the control grid and its lead. This shieldingincludes a top disc-like metal shield 3| provided with a rectangularaperture 32, as best shown in Figure 2, thru which the end of thecathode and the grid side rods extend, and issupported in spacedrelationship with respect to the mica disc It by means of small pips 33on the bottom of the disc. Attached to a collar 34 on the disc shield 3|is a box-like portion 35 which completely shields the end of the cathodeand grid side rods from the plate lead 31. This shielding is out ofcontact with the plate side rods. This upper shield may be secured tothe mount and connected by means of a pair of side rods 36, only one ofwhich is shown, to a lower shield comprising an invertedcup-shaped metalmember 31 provided with a rectangular aperture ,38 thru which the ends01' the cathode and grid side rods extend. Other apertures which theends 25 01' the fastening conductors 22 extend. This lower shield isinsulated from the mount by means of intermediate insulating disc 40-which registers with the insulating disc l9 and is provided with anaperture 4|, thru which the end of the cathode and grid side rodsextend. The ends 25 of the fastening conductors extend thru the micadisc 40 and the apertures 39 to be connected to the proper electrodes.The shields may be connected by means of a strap l2'to the cathode,which is usually at ground potential or may be provided with a separatelead. The upper and lower shields are, therefore, completely insulatedfrom the electrode mount assembly and connected to the cathode, and withthe screen grid and suppressor grid, which may be provided with aseparate lead as shown, completely shields theanode and anode lead fromthe control'grid and, control grid lead.

The electron discharge devicemade in accordance with my invention may bemounted in a specially designed tube socket as best shown in Figure 4.The socket may include a shielding partition 43, having a ring 44 ofinsulating material upon which the clip type contacts 45 may besupported toreceive the terminals 20 of the electron discharge device.-It will thus be seen that by means of this arrangement the input circuitwhich is connected to lead 26 and the output circuit which is connectedto lead 21 are completely shielded from each other.

A tube constructed in accordance with the above invention may easily bemade of very small dimensions, is sturdy and reduces interelectrodecapacity and inductance to a very small value, permitting operation ofthe tube at extremely high frequencies.

While I have indicated the preferred embodiment of my invention of whichI am now aware and have also indicated only one specific application forwhich my invention may be employed, it will be apparent that myinvention is by no means limited to the exact i'orms illustrated or theuse indicated, but that many variations may be made in the particularstructure used and the purpose for which it is employed-withoutdeparting from the scope oi my invention asset forth in the appendedclaims.

What I claim as new is:-

1. An electron discharge device including an envelope, a unitaryelectrode mount assembly positioned within the envelope and comprising apair of insulating plate members and electrodes positioned between andsecured to said members, still lead-in conductors extending thru thewall of the envelope and positioned around the periphery of one of saidinsulating plate members,

means at the inner ends of said still lead-in conductors securing theconductors to said one of said insulating plate members for supportingthe mount within the envelope and for electrically connecting theconductors to the electrodes positioned betweenthe insulating platemembers, and electrostatic shielding members positioned on opposite endsof the electrode mount assembly and secured to said insulating platemembers out of contact withsaid electrode assembly.

2. An electron discharge device including an envelope, a unitaryelectrode mount assembly po- 89 are provided thru bers and securedsitioned within theenvelope and comprising a pair or insulating platemembers, electrodes positioned between and secured to said members andhaving their ends extending thru said members, stifl lead-in theperiphery of one of said insulating plate memto said one of saidinsulating plate members and electrically connected to said electrodes,a cup-shaped metal shield positioned on the outside of said mountadjacent'said' one 10 01' said insulating plate members and providedwith an aperture thru which the ends 01' the electrodes extend, aninsulating plate member positioned between said one of said insulatingplate members and said shield to electrically insulate said shield fromthe electrodes in said mount and said stifi' lead-in conductors, andmeans for securing said shield to said mount.

3. An electron stiir-lead-in conductors positioned around the peripheryof one or said insulating plate members and secured'to said one of saidplate members and electrically connected to said electrodes.

the other end of said mount provided with a boxrods extendinglongitudinally of said mount thru said insulating plate members andsecured to said the inner ends of said lead-in conductors. said secondconductor having one end secured to' one or the insulating plate membersandthe'other end electrically connected to an electrode in saidelectrode mount assembly whereby'said mount is supported within saidtube bys'aid radially positioned lead-in conductors. a cup shapedshieldingmember secured to said one of the insulating platemembersandprovided with an aperture thru which ends of said electrodes extend, aninsulating plate member positioned between said shield and said one orsaid insulating plate memberst'oelectrically insulate said shield fromsaidilead-in conductors and said second eonductors and provided withapertures thru which said second conductors extend to be connected tothe ends of said electrodes and means for securing said shield to saidmount assembly.

amman conductors positioned around 5

